Unsaturated Soil Mechanics

Abstract

Classical soil mechanics, as presented in 1948 by Karl Terzaghi and Ralph B. Peck in their seminal text Soil Mechanics in Engineering Practice, encompasses three broad categories of soil behavior: hydraulics (flow), plastic equilibrium (stress) and settlement (volume change).Author: In first sentence of review, please consider providing a reference citation (in our REFERENCES list) for the Soil Mechanics in Engineering Practice text by Terzaghi and Peck. Copy editor Traditional methods of analyzing these types of problems have divided soils into two broad categories: fully saturated or completely dry. This simplification has allowed the development of a broad range of analytical solutions to many practical engineering problems. The text under review, Unsaturated Soil Mechanics, by Ning Lu and William J. Likos, presents methods of analysis applicable to unsaturated (partially saturated) soils. The authors divide their text into four sections: “Fundamental Principles, Stress Phenomena, Flow Phenomena,” and “Material Variable Measurement and Modeling.” The “Fundamental Principles” section includes basic physical and thermodynamic principals needed to understand and mathematically describe the behavior of unsaturated soils. Three chapters are dedicated to material properties, interfacial equilibrium, and capillarity. The material properties chapter introduces the reader to the concept of unsaturated soil as a multiphase system consisting of solid, liquid, and gas and describes the basic principles of fluid behavior (density, viscosity, partial pressure, and relative humidity). The interfacial equilibrium chapter introduces Henry's Law and Kelvin's equation. Henry's Law describes the relationship between liquids and gases at equilibrium, while Kelvin's equation describes the pressure change across a curved air-water interface (such as the air-water interface within a multiphase unsaturated soil system) as a function of the vapor pressure above the interface. The authors provide a detailed derivation of Kelvin's equation and show how it can be applied to an idealized system of capillary tubes partially filled with …